Formulations used in the elderly Flashcards
What does the success of psychotropic pharmacotherapy depend on?
treatment adherence
availability of the optimal dosage form
induction of side effects
What is the aim of novel dosage forms?
enhance drug delivery
reduce potential side effects
simplify treatment regimens
What are the types of depot oil formulations for IM injection?
oil solution
- drug is completely dissolved in oily solvent
- must partition into the surrounding aqueous medium to be absorbed
oil suspensions
- drug exists in two forms = dissolved (molecular dispersion) and undissolved (coarse dispersion)
- undissolved particles act as a drug reservoir. drug particles must first dissolve then partition into the surrounding aqueous medium
Why are oily suspensions sustained release?
due to the dissolution step needed for the coarse dispersion (undissolved particles)
What is risperdal consta?
long acting, water based atypical injection
- risperidone
risperidone is micro-encapsulated in polylactide-coglycolide (PLGA)
Why was controlled release SSRI paroxetine made?
improves general tolerability
decreases GI side effects of the immediate release form
improves patient compliance
How is CR paroxetine formed?
one layer of the tablet consist of a degradable barrier layer and the other contains the active material in a hydrophilic matrix
enteric coat delays the start of drug release until the tablet has passed through the stomach
- once in the small intestine, the drug is released over 4-5hrs
Why does the individual dose of paroxetine CR need to be 25% higher than that of the IR formulation to achieve equivalent dosing?
about 80% of the paroxetine content of the tablets is related whilst the remaining 20% is retained within each tablet
- sticks to the enteric coating
What is OROS? How does it work?
osmotic controlled release oral delivery system
- are based on an osmotic pump which is the driving force
- there are three compartments contained within a semipermeable, rigid membrane coated with the drug
1st compartment contains low concentration of drug
2nd compartment contains high concentration of drug
3rd compartment contains water reactive molecules
How does OROS work?
initial immediate release of drug
- due to the drug coating the semi-permeable membrane bursting and releasing drug
second release of drug from the first compartment via diffusion
- water is absorbed through the exposed semi permeable tablet shell
- push compartment with water reactive molecules expand releasing drug through the open orifice of the membran at a controlled rate via diffusion
third release of drug due to osmotic pressure and push pull mechanism
- drug release begins from the second compartment with a higher concentration but at a different rate
drug is released at different rates from the different compartments
What are the benefits of OROS?
fewer side effects
improved compliance
What are rapidly dissolving tablets? What are the available rapidly dissolving tablets?
tablets which disintegrate and/or dissolve rapidly in the saliva without the need for water
olanzapine - zydis
risperidone - M-tab
What are the types of transdermal drug delivery?
matrix
- 3 layer system
reservoir
- drug reservoir with a 3 layer release membrane
How does a matrix system work?
is a three layer system
1st layer is the backing film helps provide the integrity of the drug layer and keeps it protected during storage and use
2nd layer is the adhesive polymer contains uniformly distributed drug and other excipients
3rd layer is protective liner which is peeled off and discarded before the patch is used
Why can matrix systems be cut?
the drug is dispersed in a solid polymeric matrix thus the integrity of the system is maintained even if the system is cut
- there is less potential for dose dumping
- allows controlled dosing
rate of drug release is controlled by the polymeric matrix and the stratum corneum
